| | | Signal transmission and processing Kistler wheel force measuring systems are predominantly based on the extremely powerful RoaDyn System 2000 electronics concept. This combines cutting-edge digital data processing with the practical benefits of interference-resistant wireless transmission and simple networking with other measuring systems. The RoaDyn System 2000 amplifies and digitizes the signals before they leave the hub electronics. When using measuring hubs for durability test stands the digital signals are transmitted via a cable, with measuring wheels a near-field telemetry system is used. In most cases this system is on the inside of the wheel, with ring antenna and receiver accommodated in the wheel arch. This avoids any parts projecting beyond the extremities of the vehicle that could increase the drag coefficient or endanger other road users. The fact that the nearfield telemetry system follows the movements of the wheel also optimizes signal quality and eliminates the errors of a system measuring rotation angle. If there is insufficient room to mount the in-board transmission system - which is | | often the case with very small wheels and trucks - an out-board transmission unit is available as an alternative. This is mounted on the outside of the wheel and also uses digital near-field telemetry. The on-board electronics unit based on digital signal processor (DSP) technology receives the signals, filters them, performs the coordinate transformation and passes the data on to the system for acquiring measurement data in the required format. The data can be produced in analog or digital form. A variety of interfaces, such as PC parallel (EPP), CAN, Ethernet or proprietary formats of different manufacturers of measurement data acquisition systems are available for digital output. Data specific to a sensor, such as calibration values, serial numbers, etc., is saved in the particular sensor and is read by the on-board electronics when the system is started. This TEDS functionality rules out mix-ups when individual sensors are replaced as well as input errors on the part of the operator. Other properties and parameters of the measuring wheel, such as the lever arm of the force components, can be edited and archived with a configu- | | ration program. For example, the torques can relate to any point and be output in real time, and different configurations can be saved for recurrent applications. The RoaDyn System 2000 can be operated with either a handy remote control unit or an emulation program on a PC. A special RoaDyn DAQ program running under Windows makes signal recording and visualization easier, even with complex industrial test setups and a large number of channels. Measuring hubs for test stands Measuring hubs are non-spinning systems. They are used on vehicle or tire test stands and transmit their data reliably via a cable to the control room electronics. Measuring hubs for durability test stands also have System 2000 electronics and therefore basically differ in terms of the form of data transmission only, whereas the other modules are compatible with those of the measuring wheels. Measuring hubs for tire test stands usually have quartz sensors and transmit their data directly by analog means to the control room electronics. This enables scientific experiments over a wide frequency range without limitations being imposed by digital filtering or limited data transmission rates. | | |